Multi-compression unit for ammonia production

Abstract

A compression unit for ammonia comprising a multi-stage compressor, including a first set of compressor stages adapted to compress a syngas containing hydrogen and nitrogen; and a second set of compressor stages adapted to compress a refrigerant of a refrigerant circuit. Described herein is also an ammonia production system including the ammonia compression unit and a method.

1 . An ammonia-production compression unit comprising a multi-stage compressor; wherein the multi-stage compressor comprises:
 a first set of compressor stages adapted to compress a syngas containing hydrogen and nitrogen; and   a second set of compressor stages adapted to compress a refrigerant of a refrigerant circuit.   
     
     
         2 . The compression unit of  claim 1 , wherein the multi-stage compressor is a reciprocating compressor including a plurality of cylinders, wherein a first set of cylinders compresses syngas and a second set of cylinders compresses the refrigerant; and wherein a single crankshaft drives the pistons of the first set of cylinders and the pistons of the second set of cylinders. 
     
     
         3 . The compression unit of  claim 1 , wherein the first set of compressor stages comprises between 3 and 5 compressor stages; the second set of compressor stages comprises between 2 and 4 compressor stages; the first set of compressor stages is adapted to provide a compression ratio between 4 and 7; and the second set of compressor stages is adapted to provide a compression ratio between 12 and 17. 
     
     
         4 . The compression unit of  claim 1 , wherein the multi-stage compressor comprises at least one of an intercooler between two sequentially arranged stages of the first set of compressor stages; an intercooler between two sequentially arranged stages of the second set of compressor stages. 
     
     
         5 . An ammonia production system, including:
 a syngas compression unit;   an ammonia converter;   an ammonia chiller, having a hot side fluidly coupled to the ammonia converter and a cold side fluidly coupled to an ammonia refrigeration circuit; wherein the ammonia refrigeration circuit comprises a refrigerant compression unit adapted to circulate a refrigerant in the refrigeration circuit;   wherein the syngas compression unit and the refrigerant compression unit are featured by a multi-stage compressor; and wherein the syngas compression unit comprises a first set of compressor stages of the multi-stage compressor and the refrigerant compression unit comprises a second set of compressor stages of the multi-stage compressor.   
     
     
         6 . The ammonia production system of  claim 5 , wherein the refrigerant is ammonia. 
     
     
         7 . The ammonia production system of  claim 5 , further comprising an ammonia separator downstream of the ammonia chiller; wherein a syngas recirculation line fluidly connects the ammonia separator to the most downstream stage of the first set of stages. 
     
     
         8 . The ammonia production system of  claim 7 , wherein the most downstream stage of the first set of stages is adapted to process only syngas recirculated from the ammonia separator. 
     
     
         9 . The ammonia production system of  claim 7 , wherein the most downstream stage of the first set of stages is further fluidly coupled to a delivery side of an upstream stage of said first set of stages. 
     
     
         10 . The ammonia production system of  claim 5 , wherein the multi-stage compressor is a reciprocating compressor including a plurality of cylinders, wherein a first set of cylinders compresses syngas and a second set of cylinders compresses the refrigerant; and wherein a single crankshaft drives the pistons of the first set of cylinders and the pistons of the second set of cylinders. 
     
     
         11 . The ammonia production system of  claim 5 , wherein the first set of compressor stages comprises between 3 and 5 compressor stages; the second set of compressor stages comprises between 2 and 4 compressor stages; the first set of compressor stages is adapted to provide a compression ratio between 4 and 7; and the second set of compressor stages is adapted to provide a compression ratio between 12 and 17. 
     
     
         12 . The ammonia production system of  claim 5 , wherein the multi-stage compressor comprises at least one of an intercooler between two sequentially arranged stages of the first set of compressor stages; and an intercooler between two sequentially arranged stages of the second set of compressor stages. 
     
     
         13 . A method for producing ammonia, with an ammonia production system of  claim 5 , the method comprising the following steps:
 compressing syngas in the first set of compressor stages of the multi-stage compressor;   feeding the compressed syngas to the ammonia converter and producing ammonia therein;   feeding ammonia from the ammonia converter through an ammonia chiller in heat exchange relationship with a refrigerant circulating in the refrigeration circuit; and   removing heat from the refrigerant and compressing the cooled refrigerant in the second set of compressor stages of the multi-stage compressor.   
     
     
         14 . The method of  claim 13 , further comprising the following steps:
 processing chilled ammonia in the ammonia separator; and   recovering syngas from the ammonia separator and recirculating the recovered syngas through one of the compressor stages of the second set of compressor stages of the multistage compressor.